1. Field of the Invention
This invention relates to a sound isolation flexible pipe connection for use in interconnecting sections of pipelines and attenuating the transmission of sound and other vibrations through the pipeline.
2. Description of the Present Art
Flexible joints capable of interconnecting sections of pipeline in a manner whereby both fluid-borne and structure-borne vibrations within the pipeline are absorbed or dampened by the flexible joint are commonly used in situations in which it is desirable to minimize the sound generated by fluid flow, conduit expansion, or machinery-induced pipeline vibrations. Such joints are of particular value when used in submarines where it is necessary to reduce sound and vibration levels in order to prevent detection by the enemy. It is also desirable to use a flexible joint in order to accommodate for minor misalignments between the sections of pipeline which are being interconnected.
Flexible pipe joints have been previously shown in U.S. Pat. Nos. 3,734,546; 4,068,864; and 4,491,348. Such pipe joints are normally constructed of inner and outer annular collars. An elastomeric body disposed between the collars provides the desired vibration attenuating characteristics. The two collar sections are thredably secured to one another by a plurality of bolts. An O-ring seal is commonly provided at the juncture of the collars in order to give the joint the necessary fluid-tight characteristics. The end flange is likewise secured to the inner piping through use of a large diameter threaded joint. This joint is always sealed with an O-ring seal.
In use, flexible joints are exposed to cyclic flexing caused by the motions of soft mounted pumps, conduit expansion, and normal fluid flow. As a result, the threaded connections between the collars are subject to loosening, and ultimately leakage. Furthermore, the O-rings are affected by age and the fluid in contact with them, which hastens their failure while in service. In addition, the threaded connections may rattle, thus increasing the transmission of sound through the pipeline and reducing the efficacy of the flexible joint. The mechanical connections in these joints all require sufficient material to receive and secure the threaded fastener holding the joints together. In a space limited and weight sensitive application, such as a submarine, these requirements of size, weight, and reduced reliability are detrimental.